Section based hex cell routing algorithm (sbhcr)

International Journal of Computer Networks & Communications (IJCNC) Vol.7, No.1, January 2015
DOI : 10.5121/ijcnc.2015.7112 167
SECTION BASED HEX-CELL ROUTING ALGORITHM
(SBHCR)
Mohammad Qatawneh, Ahmad Alamoush and Ja'far Alqatawna
King Abdullah II School for Information Technology, The University of Jordan, Amman,
Jordan
ABSTRACT
A Hex-Cell network topology can be constructed using units of hexagon cells. It has been introduced in the
literature as interconnection network suitable for large parallel computers, which can connect large
number of nodes with three links per node. Although this topology exhibits attractive characteristics such
as embeddability, symmetry, regularity, strong resilience, and simple routing, the previously suggested
routing algorithms suffer from the high number of logical operations and the need for readdressing of
nodes every time a new level is add to the network. This negatively impacts the performance of the network
as it increases the execution time of these algorithms. In this paper we propose an improved optimal point
to point routing algorithm for Hex-Cell network. The algorithm is based on dividing the Hex-Cell topology
into six divisions, hence the name Section Based Hex-Cell Routing (SBHCR). The SBHCR algorithm is
simple and preserves the advantage of the addressing scheme proposed for the Hex-Cell network. It does
not depend on the depth of the network topology which leads to overcome the issue of readdressing of
nodes every time a new level is added. Evaluation against two previously suggested routing algorithms has
shown the superiority of SBHCR in term of less logical operations.
KEYWORDS
Hex-Cell topology, Routing Algorithm, Interconnection Topology, Networking.
1.INTRODUCTION
Routing algorithms is a popular topic in the study of computer networks, distributed systems and
their applications [1,2]. The design of routing algorithm plays an important role in determining
the performance of tightly and loosely coupled systems. The efficiency of many applications that
run on tightly and loosely coupled systems depends highly on communication time which is
affected by characteristics of routing algorithm. Routing algorithm should prove correctness,
simplicity, robustness, stability, fairness and optimality [3,4,5,6].
Several static interconnection networks and their related routing algorithms have been reported in
the literature [6,7,8,9,10]. Hex-Cell network is a class of interconnection networks which has
proposed for parallel computing systems [10,11,12,13,14]. Its topology can be constructed using
units of hexagon cells. Sharieh et al. [10] suggested the original routing algorithm in which the
addressing mode was based on the depth of the network and the position of the node in the level.
The routing from one node to another can be done using one or more of the following three
functions: moveUp, moveDown and moveHorizontal. Qatawneh et al. [11] have criticized the
dependency on the depth of Hex-Cell network which mean that the topology must be fixed
otherwise the depth value must be updated to readdress the nodes every time a new level is added.

168
Therefore, they have proposed an alternative routing algorithm in which the node addressing is
based on the address of the three cells around the node while the cell itself is addressed based on
Cartesian coordinate (X-axis and Y-axis). Their algorithm assumes the central cell is having (0,0)
as coordinate and in order to reach the destination two functions need to be used: Cell Routing
and Node Routing.
Although Hex-Cell topology exhibits attractive characteristics such as embeddability, symmetry,
regularity, strong resilience, and simplicity[10,11,12,13], the previously suggested routing
algorithms[10,11] suffer from the high number of logical operations and the need for readdressing
network nodes every time a new level is added which negatively impact the running time of that
network. Therefore, the aim of this paper is to propose a new routing algorithm for Hex-Cell
network that eliminate these shortcomings.
The rest of the paper is organized as follows. Section 2 provides an overview of Hex-Cell
network. Section 3 presents the proposed routing algorithm. Section 4 compares the algorithm to
its predecessor. Finally conclusion is presented in section 5.
2. HEX–CELL NETWORK TOPOLOGY
A Hex-Cell network [9] with depth d is denoted by HC (d) and can be constructed by using units
of hexagon cells, each of six nodes. A Hex-Cell network with depth d has d levels numbered from
1 to d, where, level 1 represents the innermost level corresponding to one hexagon cell. Level 2
corresponds to the six hexagon cells surrounding the hexagon at level 1. Level 3 corresponds to
the 12 hexagon cells surrounding the six hexagons at level 2 as shown in figure 1. The levels of
the HC (d) network are labeled from 1 to d. Each level i has Ni nodes, representing processing
elements and interconnected in a ring structure [10, 11].
Figure 1. (a) Hex-Cell with 1 level, 2 levels and 3 levels [10]
3.SBHCR ALGORITHM
The routing algorithm which is proposed in [10] depends on the depth of Hex-Cell network which
means that the topology must be fixed or there is a need for updating the depth value and
readdressing which in turns increase the setup time [11]. The number of logical operations may
increase as the depth of Hex-Cell increases which leads to more time in calculating the routing
algorithm to forward the message from one node to another. The SBHCR algorithm eliminates
the above disadvantages by proposing simple and flexible addressing mode. In order to explain
the SBHCR, we propose new addressing scheme for Hex-Cell topology which is based on the
following key assumptions:
1- The Hex-Cell topology is divided into six sections labeled from left to right (clockwise) and
numbered from 1 to 6, as shown in figure 2.

169
2- The address of each node in the Hex-Cell topology is identified by (S,L,X) where S denotes
the section number, L denotes the level number, and X denotes the node number on that
level labeled from X1,…, Xn; where n = ((2×L) - 1).
Figure 2. Hex-Cell addressing scheme for HC (3) network
A node with the address 1.1.1 is the first node that exists at the section number 1 and level
number 1. A node 1.2.1 refers to first node that exists at the section number 1 and level number 2
and so on. In SBHCR algorithm for HC as shown in Figure 3, the movement from one node to
another can be done using one of the following five cases as shown in figure 3 (a).
Figure 3.(a) The main function for the SBHCR algorithm
As an input to this routing algorithm the address of the source node (which is the first node
address) and the address of the destination node (Ssrc, Lsrc, Xsrc, Sdest, Ldest, Xdest) is used to
get the output which is the address of the second node and the address of the destination node
(Snxt, Lnxt, Xnxt, Sdest, Ldest, Xdest). Then the second node apply the routing algorithm using
the address of the source node (which is the second node address in this case) and the address of
the destination node (Ssrc, Lsrc, Xsrc, Sdest, Ldest, Xdest) to get the address of the third node

170
and the address of the destination node (Snxt, Lnxt, Xnxt, Sdest, Ldest, Xdest). We continue this
way until we reach the source address equal the destination address.
moveToUpperLevelC1(Ssrc, Lsrc, Xsrc, Sdest, Ldest, Xdest)
Output(Snxt, Lnxt, Xnxt, Sdest, Ldest, Xdest) {
If (Lsrc is odd)  return (Ssrc, Lsrc + 1, Xsrc + 1, Sdest, Ldest, Xdest)
Else
If (Xsrc < Xdest)  return (Ssrc, Lsrc, Xsrc + 1, Sdest, Ldest, Xdest)
Else  return (Ssrc, Lsrc, Xsrc - 1, Sdest, Ldest, Xdest) }
---------------------------------------------------------------------------------------------------------------------
moveToLowerLevelC1(Ssrc, Lsrc, Xsrc, Sdest, Ldest, Xdest)
Output(Snxt, Lnxt, Xnxt, Sdest, Ldest, Xdest){
If (Lsrc is even)  return (Ssrc, Lsrc - 1, Xsrc - 1, Sdest, Ldest, Xdest)
Else
If (Xsrc ≤ Xdest)  return (Ssrc, Lsrc, Xsrc + 1, Sdest, Ldest, Xdest)
---------------------------------------------------------------------------------------------------------------------
If (Xsrc is even)  return (Ssrc, Lsrc - 1, Xsrc - 1, Sdest, Ldest, Xdest)
Else
If (Xsrc + 1 > ((2 × Lsrc) – 1))
If (Ssrc = 6)  return(1, Lsrc, 1, Sdest, Ldest, Xdest)
Else  return (Ssrc + 1, Lsrc, 1, Sdest, Ldest, Xdest)
Else  return (Ssrc, Lsrc, Xsrc + 1, Sdest, Ldest, Xdest)}
---------------------------------------------------------------------------------------------------------------------
If (Xsrc is even)  return(Ssrc, Lsrc - 1, Xsrc - 1, Sdest, Ldest, Xdest)
Else
If (Xsrc + 1 > ((2 × Lsrc) – 1))
---------------------------------------------------------------------------------------------------------------------
Else
If (Xsrc - 1 < 1)
If (Ssrc = 1)  return (6, Lsrc, ((2 × Lsrc) – 1), Sdest, Ldest, Xdest)
Else  return (Ssrc - 1, Lsrc, ((2 × Lsrc ) – 1), Sdest, Ldest, Xdest)
---------------------------------------------------------------------------------------------------------------------
Else
If (Xsrc - 1 < 1)
---------------------------------------------------------------------------------------------------------------------
moveSameLevelC1(Ssrc, Lsrc, Xsrc, Sdest, Ldest, Xdest)
If (Xsrc < Xdest)  return (Ssrc, Lsrc, Xsrc + 1, Sdest, Ldest, Xdest)
Else  return (Ssrc, Lsrc, Xsrc - 1, Sdest, Ldest, Xdest)}
---------------------------------------------------------------------------------------------------------------------
If (Xsrc + 1 > ((2 × Lsrc) – 1))
---------------------------------------------------------------------------------------------------------------------
If (Xsrc - 1 < 1)
Else  return (Ssrc, Lsrc, Xsrc - 1, Sdest, Ldest, Xdest)}
Figure 3.(b) The sub-functions the SBHCR algorithm

171
4.SCENARIO BASED DISCUSSION
The following examples explain the above routing cases. For this purposed, we consider a
network of a Hex-cell topology with 4 levels; i.e. HC (4) as shown in Figure 4.
Figure 4. HC (4) topology with labeled nodes and levels
Scenario 1: The source and destination in the same section and level
Let (Ss.Ls.Xs) = (2.4.2) be the source node and (Sd.Ld.Xd) = (2.4.7) be the destination node. When
executing the routing algorithm, CASE 1 will be applied. To reach the destination, the algorithm
goes through five steps; i.e., (2.4.2) → (2.4.3) → (2.4.4) → (2.4.5) → (2.4.6) → (2.4.7) , as
shown in Figure (5).
Figure 5. The source and destination in the same section and level
Scenario 2: source and destination are in the same section and different levels
(destination level less than source level)

172
Let (Ss.Ls.Xs) = (5.4.5) be the source node and (Sd.Ld.Xd) = (5.2.1) be the destination node.
When executing the routing algorithm, CASE 1 will be applied. To reach the destination, the
algorithm goes through four steps; i.e., (5.4.5) → (5.4.4) → (5.3.3) → (5.3.2) → (5.2.1), as shown
in Figure (6).
Figure 6: source and destination are in the same section and different levels
(destination level less than source level).
Scenario 3: source and destination are in the same section and different levels
(source level less than destination level)
algorithm goes through five steps; i.e., (5.3.2) → (5.3.3) → (5.4.4) → (5.4.5) → (5.4.6) →
(5.4.7), as shown in Figure (7).
figure 7. Source and destination are in the same section and different levels
(source level less than destination level)
Scenario 4: source and destination are in different sections (Ss = Sd - 1 or Ss = Sd + 5)
(source level less than or equal destination level)

173
algorithm goes through six steps; i.e., (1.3.2) → (1.3.3) → (1.3.4) → (1.3.5) → (2.3.1) → (2.4.2)
→ (2.4.1), as shown in Figure (8).
Figure 8. Source and destination are in different sections (Ss = Sd - 1 or Ss = Sd + 5)
(source level less than or equal destination level).
Scenario 5: source and destination are in different sections (Ss = Sd - 1 or Ss = Sd +
5) (destination level less than source level)
algorithm goes through six steps; i.e., (1.4.4) → (1.3.3) → (1.3.4) → (1.2.3) → (2.2.1) → (2.2.2)
→ (2.2.3), as shown in Figure (9).
Figure 9. Source and destination are in different sections (Ss = Sd - 1 or Ss = Sd + 5)
Scenario 6: source and destination are in different sections (Ss = Sd – 2 or Ss = Sd + 4)

174
algorithm goes through nine steps; i.e., (4.3.2) → (4.2.1) → (4.2.2) → (4.1.1) → (5.1.1) → (6.1.1)
→ (6.2.2) → (6.2.3) → (6.3.4) → (6.3.3), as shown in Figure (10).
Figure 10. Source and destination are in the different sections (Ss = Sd - 2 or Ss = Sd + 4)
Scenario 7: source and destination are in different sections (Ss = Sd - 3 or Ss = Sd + 3
or Ss = Sd - 4 or Ss = Sd + 2 )
goes through eleven steps; i.e., (6.3.3) → (6.3.4) → (6.2.3) → (1.2.1) → (1.2.2) → (1.1.1) →
(2.1.1) → (3.1.1) → (3.2.2) → (3.2.3) → (3.3.4) → (3.3.3), as shown in Figure(11).
Figure 11. Source and destination are in different sections
(Ss = Sd - 3 or Ss = Sd + 3 or Ss = Sd - 4 or Ss = Sd + 2 )
Scenario 8: source and destination are in the different sections (Ss = Sd - 5 or Ss = Sd
+ 1) (source level less than or equal destination level).
goes through eight steps; i.e., (5.2.3) → (5.2.2) → (5.2.1) → (4.2.3) → (4.3.4) → (4.3.3) →
(4.4.4) → (4.4.3) → (4.4.2), as shown in Figure (12).

175
Figure 12. Source and destination are in the different sections (Ss = Sd - 5 or Ss = Sd + 1)
(source level less than or equal destination level).
Scenario 9: source and destination are in different sections (Ss = Sd - 5 or Ss = Sd + 1)
goes through five steps; i.e., (5.4.4) → (5.3.3) → (5.3.2) → (5.2.1) → (4.2.3) → (4.2.2), as shown
in Figure (13).
Figure 13. source and destination are in different sections (Ss = Sd - 5 or Ss = Sd + 1)
5.COMPARISON BETWEEN SBHCR AND OTHERS ALGORITHMS
The original Hex-Cell routing [10] uses a centralized algorithm to find the best path from the
source to the destination. This means that one node do the job, and it is same in the alternative
algorithm proposed in [11]. In the contrary, in the SBHCR each node finds the best next node in
order to get to the final destination. Thus, the total number of required operation to perform

176
logical comparison is divided on the nodes, which would give better performance when compared
with a single node performing the same logical operation.
Table 1. Comparison between SBHCR and others algorithms.
For instance, the number of steps and logical comparison between two same nodes:
1) Original routing algorithm [10]:
a) From node (4.8) to (5.8) it takes 3 Steps and need 13 Logical Operations
b) From node (3.7) to (6.7) it takes 5 Steps and need 21 Logical Operations
2) Alternative Routing Algorithm [11]:
a) From node ((1,-1),(0,0),(1,1)) to ((-1,-1),(0,0),(-1,1)) it takes 3 Steps and
need 25 Logical Operations
b) From node ((1,-1),(2,0),(1,1)) to ((-1,-1),(-2,0),(-1,1))it takes 5 Steps and
need 85 Logical Operations
3) SBHCR Algorithm
a) From node (2.1.1) to (5.1.1) it takes 3 Steps and need 22 Logical
Operations
b) From node (2.2.2) to (5.2.2) it takes 5 Steps and need 32 Logical
Operations.
6.CONCLUSION
In this paper we propose a new routing algorithm for Hex-Cell network that eliminates the
weaknesses of the previously suggested algorithms. The algorithm is based on dividing the Hex-
Cell topology into six divisions and called Section Based Hex-Cell Routing (SBHCR). The
SBHCR algorithm is simple and preserves the advantage of the addressing scheme proposed for
the Hex-Cell network. The SBHCR does not depend on the depth like the current addressing
which means that the network can be extended without reconfiguration the whole network.
Moreover, in this algorithm the task of finding the best routing path is performed by more than
one node which implies better performance.
Proposed
Routing
Algorithm
Routing Algorithm in [11]Original Routing
Algorithm [10]First Cell Level
333Number of Steps
232513Number of Logical Operations
sum, sub and
mod
sum and subsum, sub and modArithmetic operation
Second Cell Level
555Number of Steps
328521Number of Logical Operations
sum, sub and
mod
sum and subsum, sub and modArithmetic operation

177
REFERENCES
[1] A
[2] Chatterjee, Pushpita. "Trust based
-
[3] Decayeux, Catherine, and David Seme. "3D hexagonal network: Modeling, topological properties,
addressing scheme, and optimal routing algorithm." Parallel and Distributed Systems, IEEE
Transactions on 16.9 (2005): 875-884.
[4] Tse-Yun Feng; Seung-Woo Seo, "A new routing algorithm for a class of rearrangeable networks,"
Computers, IEEE Transactions on , vol.43, no.11, pp.1270,1280, Nov 1994 doi: 10.1109/12.324560.
[5 ]Chen, Chi-Chang, and Jianer Chen. "Nearly optimal one-to-many parallel routing in star networks."
Parallel and Distributed Systems, IEEE Transactions on 8.12 (1997): 1196-1202.
[6] Mohammad, Qatawneh. "Adaptive fault tolerant routing algorithm for Tree-Hypercube
multicomputer." Journal of Computer Science 2, no. 2 (2006): 124.
[7] Li, Keqin. "Parallel processing of divisible loads on partitionable static interconnection networks."
Cluster Computing 6, no. 1 (2003): 47-55.
[8] Dündar, Pinar. "Stability measures of some static interconnection networks." International journal of
computer mathematics 76, no. 4 (2001): 455-462.
[9] Abd-El-Barr, Mostafa, and Fayez Gebali. "Reliability analysis and fault tolerance for hypercube
multi-computer networks." Information Sciences 276 (2014): 295-318.
[10] Ahmad Sharieh, Mohammad Qatawneh, Wesam Almobaideen, Azzam Sleit, Hex-Cell: Modeling,
Topological Properties and Routing Algorithm, European Journal of Scientific Research, 22:2(2008),
457-468.
[11] Mohammad Qatawneh, Hamed Bdour, Shrouq Sabah, Rana Samhan, Azzam sliet, Ja'far Alqatawna,
Wesam al-Mobaideen. An alternative Routing Algorithm for Hex-Cell network. Information: An
International. Information: an international interdisciplinary journal. 14(10). Pp.3499-3514. 2011.
[12] Mohammad Qatawneh, Embedding Binary Tree and Bus into Hex-Cell Interconnection Network.
Journal of American Science, 2011; 7(12).
[13] Mohammad Qatawneh, Bdour Hamed, Wesam AlMobaideen, Azzam Sleit, Amal Oudat, Wala’a
Qutechat, Roba Al-Soub, FTRH: Fault-Tolerance Routing Algorithm for Hex-Cell Network. IJCSNS
International Journal of Computer Science and Network Security, VOL.9 No.12, December 2009.
[14] Mohammad Qatawneh, Multilayer Hex-Cells: A New Class of Hex-Cell Interconnection Networks
for Massively parallel Systems. Int. J. Communications, Network and System Sciences, 4(11) 2011.

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